Remove misplaced suicide code.

textdownload.php

@@ -14,8 +14,6 @@
 // You should have received a copy of the GNU General Public License
 // along with Stack.  If not, see <http://www.gnu.org/licenses/>.
 
-defined('MOODLE_INTERNAL') || die();
-
 /**
  * This script serves text files generated on demand by rendering CASText
  * of a given question with a given seed. For generated data transfer needs.